In that activity of the rabbit oviductal musculature appears to be involved with gamete transport, studies are being conducted in an attempt to reveal the neural (autonomic nervous system)- endocrine (ovary) control of tubal contractility. Current data from this laboratory have shown that adrenergic alpha activity predominates in the tubal isthmus, and alpha and beta activity are stimulatory and inhibitory, respectively. In addition, adrenergic alpha and beta activity are closely related to estrogen and progesterone, respectively. The cholinergic influence upon the tubal musculature is currently being studied. Both in vivo and in vitro studies indicate that cholinergic stimulation increases musculature tone but to a lesser degree than adrenergic alpha stimudation. It would appear that most of the cholinergic stimulation is mediated indirectly through post-ganglionic adrenergic fibers. Current studies are being conducted to quantify the degree of direct cholinergic and indirect adrenergic parasympathetic influence upon the oviductal isthmus. Surgical alteration of the rabbit reproductive tract did not reveal the presence of a specific utero-tubal pacemaker region essential for sperm cell transport into the oviduct. In contrast, studies involving contraction of the tubal isthmus suggest that the ampullary isthmic junction (AIJ) may be essential for normal activity of the isthmic musculature.